Dowser-control mechanism for motion-picture-projecting machines



7 A g- 9 I T. T. ALLEN ET AL 1,725,556

DOWSER CONTROL MECHANISM F OR MOTION PICTURE PROJECTING MACHINES Filed June 11, 1928 5 SheetsSheet 1' IN VENTORS:v

I V I 61 Jalm f-dmzlmm Qf g jsi l aihersjum ..f BY M V I 1 Aug. 20, T. T ALLEN ET AL 1,725,556

DOW-SEE CONTROL MECHANISM FOR MOTION PICTURE PROJECTING MACHINES Filed June 11, 1928 5 Sheets-Sheet 2 71,10 IN V EN 7;?55:

mas n v -BY 9: I ATTORNEY WITNESSES:

T. T. ALLEN ET AL Aug. 20, 1929.

DOWSER CONTROL MECHANISM FOR MOTION PICTURE PROJECTING MACHINES 5 Sheets-Sheet 5 Filed June 11. 1928 rim Wmvrssrs INIQVTORS: .EknDit ni' W ATTORN Aug? 1929-- T. T. ALLEN ET AL. 6

'DOWSER CONTROL MECHANISM FOR MOTION PICTURE PROJECTING MACHINES Fil June 1928 5 Sheets-Sheet 4 m0 mix 15 01 JMWZ: Zia-ms ATTORNEY Aug. 20, 1929.;

T. T. ALLEN ET AL DOWSER CONTROL MECHANISM FOR MOTION PICTURE PROJECTING MACHINES Filed June 11, 1928 5 Sheets-Sheet 5 Tia-=5- INVENTORS: fiamas 214 5 1 JfihnFazwz-sAdam BY J. Sirwikers ,DZZIZIYQ ATTORNE-Y WITNES s rs Patented Aug 20, '1929J UNITED s'rArss PATENT eerie THOMAS TWADIDEL ALLEN, JUEN FRANCIS F PHILADELPHIA, PENNSYLVANIA, ASSIGNORS TO SENTRY CORPORATION, OF PHILADELPHIA, PENNSYLVANIA, A

WARE.

DOWSER-CONTROL MECHANISM FOR MOTIONJPICTURE-PROJEGTING- Application filed June 11,

This invention relates to dowser control mechanism for motion picture projecting machines.

It has for its object the collocation of control units in a single compact casing of pleasing design. The object therefore may be said to be to provide dowser control mechanism simple in construction and efficient in operation.

it is not contended. that all of the devices are new in principle but the several mechanisms are so designed and arranged that the coordination of parts will produce a simplified mechanism in compact form capabie of r performing all the functions of hitherto unrelated elements and devices.

According to the invention, the dowser control HIGCilH-IllSll'l is mounted within a closed casing and'comprises means to pre- 43 vent the raising of the dowser out ol light obstructing position until the film is moving with sullieient apidity across the projection aperture, a motor switch for operating the him feeding mechanism and controlled by moving the dowser to a certain predetermined point which will not move it out of light obstructing position, magnetic means which, upon the movement or the iilm at the required rate of speed, will permit the dowse'r to be raised out or light obstructing position, means for releasably holding the dowser in said last position, means operated by said. magnetic means for releasing the means which holds the dowser out oi light obstructing position to permit the same to fall. by

gravity into light obstructing position, manual meaus itor permitting the dowser to drop into light obstructing position, and release means l'or permitting the dowser to be raised out bi? light obstructing position at any time.

The drawings illustrate an embodiment of the dowser control mechanism and the views therein are as follows v lFigiiire i is a front elevation of the dowser, the casing which contains the control mechanism and the cone through which the rays from the are light pass, and in this figure the dowser is shown in a position to close the motor circuit to permit the film feeding mecha nism to Lather sutiicient speed to allow the dowser to be raised out of light obstructing position,

ADAMS, AND JOHN STRUTEERS DUNN, SAFETY CONTROL CORPORATION OF DELA- MACHINES.

1928. Serial No. 284,320.

Figure 2 shows the cone with p the casing or the dowser operating I mechanism in vertica-i section w th the mechanism therein however in full with the exception of a bracket at the iower part which has been broken away and in this view the dowser has been shown in light obstructing position,

Figure 3 is a rear view ng the cover removed to disclose the operatng mechanism and in this view the dowser is in light obstructing position,

Figure i: is a vertical section taken substantiahy on the line of Figure 2 including the complete mechanism and looking in the direction oi the arrows; in this figure the parts are shown with the dowser in position for operating the motor,

Figure 5 is a vertical section similar to Figure in that it is taken on the line i&- of Figure 2 but shows the arrangement of the parts when the dowser has been raised out of light obstructing position,

Figure 6 is a horizontol section through the dowser control mechanism casing and is taken on the line 8-6 of Figure 3 looking in the direction of the arrows, and

Figure 7 is a vertical section taken on the line ?-7 of Figure The dowser control mechanism is contained in a casing-ll which has an integrally formed foot 12 for mounting the same upon the cone ii of the lamp housing (not shown) of a motion picture projecting machine. The method oi attaclm'ieut is shown to be by the screws 1 but it will be understood that while the cone forms a suitable support for the mechas nism, it is shown thereon-merely a convenient means of support and the foot may be eliminated and any other form of mount-- ing may be used,

The casing has a cover 16 which complete ly closes the operating mechanism therein and this cover has a bearing 17 formed integrally therewith for the purpose of housing a shat 18 which extends through said casing an d through a sleeve 19 in the b arin 520 formed on the end wall 21 of sai r casin dowser arm 22 is tired to the end 0' haft bv the screw 23 which l sses through the shanl: 2i and throu h sa l i r dowser and is formed arm extends bciow the shanl; Q-i

1 w .e I for supporting on each side eLlQlQOL a plate of the casing showand a 26, which plates are secured thereto and to each other'by the rivets or other fastening means 27. t

The front of the-casing 11 is providedwith,

an integrally formed stop 28 and rib '29 for reinforcing said stop.

The upper end of the dowser 'arm' is provided with an operating handle 31 which is ward by the spring 34 fastened to the screw The downward movement- 36in said arm. of the latch 33 is limited by the shape of the socket in which the handle is pivotally mounted. Thev inner side of the end wall 21 of the casing 11 isprovided with an integral rib 37 against which a substantially circular mounting plate 38 abuts by its flat upper end 39, and this plate is held in position against the inner face of the end wall 21 by means of the screws 41.

The upper end of the casing is provided at its front with an inclined surface 42 beond which is a notch 43 for receiving the latch 33 on the operating handle 31- and beyond this notch 43 is a shoulder 44 for limiting the movement of the dowser arm.

Whenthe dowser falls into light obstructing position, as will be later explained, the latch 33 rides'up the inclined surface 42 and drops into the notch 43 where it is securely held with the dowser 46 formed-by the plates 26 directly in front of the source of light and obstructing the passage of said light from its source to the film which lies across the proecting aperture.

The mounting plate 38 is provided with-a pair of upstanding supports 47'to which is attached an angular magnet frame 48. This magnet frame has securely fixed thereto an electro-magnet 49. The upper part of this angular magnet frame'is provided at its outer end with a cut-backportion which provides end lips 51 which extend into recesses 52 on the sides of the keeper 53 so as to vertically position said keeper. The magnet 49 is located off-center and in an oblique posi-.

tion as shown in Figure 3, and. the lower end of the keeper is provided with a.we1ght 54 for accentuatmg its action when it is released by the influence of the magnet. The upper 1 end of the keeper is provided with a screw 56 to the end of which is attached a spiral spring 57 and this spring has its other end fastened to a post 58 on the upper end of the angular magnet frame so that, when the magnet is deenergized the spring 57 will assist the weight 54 in pulling the keeper 53 to the position shown in Figure 3.

A control plate 59 is located near the inner end of the keeper 53 and, when the keeper is drawn over against the magnet, this plate is almost parallel therewith, as shown in Figure 5. The control plate has a U portion 61 and a leg 62 which is adapted to engage with the upper end of the angular magnet frame 48. This plate 59 .is pivotally supported by means of the overhanging portions 63 through which the screw 64 extends and on which the same has a limited pivoting action. This plate is also provided at a point opposite the lower end of the keeper 53 with a set screw 66 which is regulated by means of the slot 67 in its screw end and locked in position by means of the lock nut 68.

This plate has an outstanding lug 69 near the lower end thereof and extending out upon that side nearest the inner end of the casing and on its other side it is provided with a notch 71, the upper end of which is reinforced by a small plate 72 which is riveted to said platch and whose outer end 73 is turned onto the material forming said notch to provide a wearing surface. Near the upper end of the plate 59 is a finger 74 which is struck out from the material forming the plate and one end of a spiral spring 76 is connected to'said finger while the other end of said spring is firmly connected to a finger 77 which is struck out from theniounting. plate 38.

The plate 59 is limited in its outward movement by means of the limiting screw 7 8 which is mounted in the shoulder 7 9 struck up from the mounting plate 38 and this screw may he regulated as desired and is locked in the position by means of the lock nut 81.

The sleeve 19 passes through the mounting plate 38 and has a collar 82 which abuts said plate. Immediately beyond this collar and fixed to the shaft by the pin 84 which extends through the same is a cam 83. A latch 86, which has an overhanging finger 87, is provided with a circular portion 88 which fits around said shaft and which; is fastened to the cam 83 by a screw or ritiet 89 so that said latch moves with said cam. y

A U-shaped bracket 91 is fastened to the mounting plate 38 by the screws 92 and the outer face 93 of said bracket is'provided .with a thin strip of insulation-94 against which an insulating plate 96 rests and which isfastened to the bracket. This insulating plate is'suitably secured to the said bracket and has secured to its outer face oppositely dis- )osed brackets 97 and 98 which are each provided with binding posts 99. and 101 respectively on the outer ends thereof. I The insulating plate 96 is provided with a pair of posts 102 and 103 upon which are pivotally mounted contact arms 104 and 106 respectively. The shaft 18 cut-out as at 107 to form avcam face and the opposed face of the contact arm 104 is provided with inis adapted to rest against the upstandinglinr iting arm 11.3 on the outer contact arm 106. The pivoted end ot'the contact arm 10% has an cut-turned end 11 1 which is engaged by one end of a spiral spring 116 while the other end or said spring is fastened to the bracket 98. A bracket 117 is provided just below and near the longitudinal center of the binding post 118. The contact 106 has an out-turned end 119 to which one end of a spiral spring 121 is attached while the other end of said spiral spring is attached to the bracket 117.

By reason of these connections and the action of the springs 116 and 121, it will be seen that the contact points 122 and 123 on the outer ends of the contact arms 10%- and 106 respectively will each have a tendency to move toward the center of the mounting plate 38 andthe insulation 108 on thecontact arm 10a will therefore bear'against the shaft 18. and against the cam face 107 while the outer contact arm, although having a tendency to move in said direction, will be prevented trom having its contact point 123 engaged with the contact point 122 of the contact arm 104. By reason of the limiting screw. 111 which is so arranged that when-the shaft 18 is in the position shown in Figure 7 the cam face 107 will bear against the insulation 10S and thus allow the contact point 122 to move far enough inward to keep it away from the contact point 123 which is limited by the screw 111. 1

At a point innnediately back of the groove 43, the casing is 'providedgvith a sleeve 12% which screws into a tap hole in said casing and the rod 126 extends through said sleeve and has a button 127 on its outer end. The inner end of a rod 126 rests upon the flat part of the leg 62 and is not of sullicient weight to overcome the action or the spring 76 except when pressure is placed thereon.

Pivotally mounted on the mounting plate 38 by the screw 128 is a level 129 which e21 tends through the side of the casing and its inner end 131 extends over and slightly above the iiat part of the leg 62 when it is in normal position and drawn to the position shown in Figure 1 by means of the spring 152 which is attached at an outward position beyond the pivotal pointby its one end and to a post 133 on the mounting plate 38 by its other end. This lever has a wire or cord 130 tied through the hole 125 on the outer end thereof.

At the lower part of the casing is a release 13% whose inner end 135 is adjacent the lower end of the control plate 59 when the same is its outward position, as shown in Figure This release consists of a rod 1.37 which extends through a sleeve 138 passing through the casing and has a button 139 on the outer end thereof normally pressed outward by the spring 1 11 which surrounds said rod.

The casing has a hole extending through one side of the same for the entrance of the are the usual safety switches in the usual manner.

Fora complete understanding oil the wiring see the copending application of two of the applicants hereto, Thomas T. Allen and John Francis Adan1s,-liled September 23rd, 192?, Serial No: 221,491. r

The operation of the improved dowser con trol mechanis i is as tollows Let us co ider that the dowser is in light obstructing position as shown in Figure The latch oo will rest in the groove 13, the magnet 49 will be deenergized and the contact points 122 and 12;) or the switch will be opened and in the position shown in Figure 7.

ln order to start the motor for feeding the film, the dowser is then moved to the position shown in Figures 1 and 4;. This is accomplished by pressing the operatinghandle 31 downward so as to release the latch 33 from the groove 13 and then swinging the same to the position just mentioned. The dowser is prevented from moving beyond that position by reason of the overhanging linger 87 of the latch 86 resting against the outstanding lug on the lower end of the control plate 59. This plate is held in position so as to engage this latch by means or the magnet keeper which is swung outward by the spring 57 and which engages the set screw 66 on said plate.

hen the dowscr has been moved to the position shown in Figures 1 and 4t, the shaft 18 will have been slightly rotated so that the cam 10'? (see Figure 7) will have pressed the contact arm 101 outward and engage the contact points122 and 123. The closing of these contacts closes the motor circuit and (arises the film to be fed across the aperture plate (not shown).

When the film feeding mechanism "Falls below a certain speed, the centrhugal switch or other device will short-circuit the electromagnet 49 and release the keeper 53 huh on the other hand, when the film feeding inechanism attains a predetermined speed. the magnet will be energized through the operation of the centrifugal switch or other device so that the keeper 53 will be drawn to ward the same and held thereby. The spring It will swing the control plate 59 to the position shown in Figure 5, thereby pulling the outstanding lug 69 over and out of the path of the finger 87 on the latch 86 so that the dowscr I with'the tip of control plate 59 to the position may then be swung into the position shown in Figure 5, and the latch 86 will pass over the lug and be drawn to the position shown in said figure. The cam 83 will also have been' rotated as therein shown and the cam will have engaged by its curved outer face the outer end 73 of the plate 72 in the notch 7-1 during the rotation'oftlie shaft.

Of course, this will have placed a slight tension on the spring 76 and the set screw 66 will have been held slightly away from keeper 53. When, however, the reaches theposition'show'ndn Figure 5, the curved outer face of the cam will have passed the plate 72 so that the spring 76 will draw the shown in Figure 5 where the head of the set screw 66 wii rest firmly against the keeper 53 and the cam I ce 100 will engage the end of the plate 72 1hr reby locking the dowser into its raised position so that the rays from the lamp will pass through the cone 13 to project the images on thefilm. The upward movement of the dowser to the position just described is limited by the dowser arm 22 striking against the stop 28 on the front of the casing-1L It might be saidat this point that when it is desired to use the projecting machinefor projecting images on slides, as distinguished from films, the operation just described for permitting the raising of the dowser may be accomplished by pressing the button 139 so that the inner end 135 of the release will engagethe bottom of the control plate 59 and swing the same aside so as to permit the disengagement of the finger 87 on the latch 86 from the lug 69 on the lower end of said plate and the dowser can then be swung to the film,

in Figure 5 by the manual dowser arm 22. The dowser control mechanism is intended to be included in a circuit where there are safetyswitches which, upon the breaking or clogging of the the breaking of a'motor transmission belt. or the blowing of the fuse-of the motor, will deenergize the magnet 49.

These switches have been shown in nu-i merous applications" filed by the applicfants Allen and Adams herein, and it is believed position shown that the illustration of such devices is unthat when any of necessary. Suffice to say the magnet these defectsv in operation occur, 49 is deenergized. I v

When the magnet is deenergized, the weighted keeper 53 will fall outward, as shown in Figure 3, and will be assisted in this action by the spring 57 connecting the upper end thereof with the post 58. As this bears against the head of the set screw 66 in the control plate 59, such plate will be swung outward on its pivotal peint 64 and theegagement between the cam face 100 andthe outer endjofthe plate 72 will be broken and the dowser will fall by, gravity to the posie; dowser "coming a' nr contactu tion shown in" Figure 3 and it will be prevented from bouncing by the latch 33 riding up the inclined face 42 anddropping into the groove 43.

As the dowser fails it will of course rotate the shaft 18 and this shaft willbe rotated to the position shown in Figure 7 so that the cam 107 will rest with its face flat against the insulating plate 108 on the contact arm 104 and the spring 116 will pull the outer end of this contacting'arm inward so as to disengage the contact points 122 and 123.

It will be understood that while the contact arm 106 is also urged inwardly by the spring'121 thatfthe set screw 111 in the bracket 109 will prevent the contact point 123 from following the contact point 122. The manual closing down of the projecting inachine may be accomplished by pressing down ward on the button 127 so that the rod 126 will press downward on the flat part of the leg 62 on the control plate 59 (see Figure 5) so that the tension of the spring 76 is overcome and. the control plate swung outward as before described to disengage the cam 83 from the plate 7 3-in the notch 71. This will of course permit the dowser .to fall in precisely the same manner as though the device were automatically operated.

For the purpose of closing the dowser and stopping the motor from a remote point, the lever 129 has been provided so that upon drawing upward on the outer end thereof through the medium of the wire or cord 130, the inner end of said lever will strike against the fiat part of the leg 62 and will swing the control plate out in the manner just described.

The dowser which is formed by the two plates 26 provides an air-space between the same for the purpose of dissipating the heat from the are when the dowser is lclosed'by the circulation of air through the said space.

It has been found in practice that where a single'plate isemployed the same becomes very hot and may even cause damage to the film where the film is at rest over the aperture and the arc is maintained. Persons plate have also been severely. burned. With the use of the double plate which dissipates the heat both the film and the operator are protected from injury.

Of course, the dowser control mechanism illustrated may be modified in various ways without departing from the invention herein set forth and hereafter claimed. Y The invention is hereby claimed as follows.

-W'e claim j 1. A dowsercontrol mechanism for motion .picture projecting machines comprising an electro-magnet, a keeper, a shaft upon which a dowser ismou'nted, a latch and a cam mounted on said shaft and rotatable therewith, a

with the'single dowser control plate swingably mounted. and having means positioned by the keeper for engaging said latch to prevent the turning of said shaft and arising or said dowscr when the magnet isdeencrgiaed, said plate being arranged to swing and disengage said means and latch when the magnet is energized and the keeper drawn thereto and means on said plate engaging said cam for holding said dowser in a raised position when said mag net is energized.

2. A dowser control mechanism for motion picture projecting machines comprising an electro-magnct, akccper, a shatt upon which a dowser is mounted, a latch and a cam mounted on said shaft and rotatable therewith, a swingable control plate, means on said control plate positioned by the keeper for engaging said latch to prevent the turning or? said shaft and the raising of said dowser when the magnet is deenergized, said plate being a ranged to swing and disengage said means and latch when the magnet is energized and the keeper drawn thereto, and means on said plate engaging said cam for holding said dowser in a raised position when said magnet is energized.

3. A dowser control mechanism for. motion'picture projecting machines comprising an electromagnet, a keeper, a shaft upon which a dowser is mounted, a latch and. a cam mounted on said shaft and rotatable therewith, a swingable control plate, an outstanding lug on. said controlplate positioned by the keepe :tor engaging said latch to prevent the tnrni of said shaft and the raising of said dowse when the magnet is deener giZed, -said plate being arranged to swing and l said lag and latch when the mod and the keeper drawn ther to, and means on said plate engaging said cam for holding said dowser in a raised position when said magnet is energized.

4. A dowser control mechanism tor motion picture projecting machines comprising an electro-magnet, a keeper, a shaft upon which a dowser is mounted, a latch and a cam mounted on said shaft and rotatable therewith, a swingable control plate 'havlngmeans for swinging the lower end thereof outward when the magnet is deenergized, an outstanding lug on said control plate positioned mounted on shaft and rotatable therewith. a swingable control plate, means on said control plate positioned by the keeper for engaging said latch to prevent the turning or said shaft and the raising of said dowscr when the magnet is deencrgized, said plate being arranged toswing and disengage said means and latch when the magnet is energized and the keeper drawn thereto, and a notch in the lower end of said plate for receiving said cam to hold said dowser in a raised position when said magnet is energized.

A dowser control mechanism for motion picture;projecting machines comprising an electronagnet, a keeper, a shaftupon which a dowser is mounted, a latch and a cam mounted on said shaft and rotatable therewith, a swingable control plate adapted to have the lower end thereof swung outward by the keeper when the magnet is deenergized, means on said control plate for engaging said latch when the lower end of said control plate is swung outward. said plate being arranged to swing and disengage said means and latch when the magnetis energized and the keeper drawn thereto, and a notch in the lower'end of said plate for receiving said cam to hold said dowser in a raised position when said magnet is energized.

' 7. A dowser control mechanism for motion picture projecting machines comprising an elcctro-magnet, a keeper, a shaft upon which a-dowser is mounted, a latch and a cam mounted on said shaft and rotatable therewith, control plate having means positioned by the keeper for engaging said latch to prevent the turnin of said shaft and raising of said dowser when the magnet is deenergized, said by the keeper for engaging said latch when the lower end or" said control plate is swung outward, said plate being arranged to swing and disengage said lug and latch when the magnet is energized and the keeper drawn thereto, and means on said plate engaging said cam for holding said dowser in a raised position when said magnet is energized.

5. A dowser control mechanism for motion picture projecting machines comprising an electro-magnet, a keeper, a shaft upon which a dowser is mounted, a latch and a cam plate being arranged to swing and-disengage said means and latch when the ma gnet is energized and the keeper drawn thereto, means on said plate engaging said cam for holdings'aid dowser-in' a raised position when said magnet is energized, a motor switch, and means onsaid shaft for opening said switch when the magnet is deenergized and the dowser falls into light obstructing position.

8. A dowscr control mechanism for motion picture projecting machines comprisin an electromagnet, a keeper, a shaft upon wnich a dowser is mounted, a latch and a cammonnted on said shaft and rot-ata ole therewith, a s'wingable control plate, means on said contrcl plate positioned by the keeperfor engag ing said latch to prevent the turning of shaft and the raising of said dowser the magnet is deenergized, said plate be ranged to swing and disengage said and latch when the magnet is energized and the keeper drawn thereto. 11 cans on said plate engaging said cam tor ho M ng said do riser in a raised position when said magnet ener gi zed. a motor switch.and means on said shaft for opening said switch when the magnet is deenergized and the dowser falls into'light obstructing position. i

9. 'A dowser control mechanism for motion picture projecting machines comprising an electro-magnet, a keeper, a shaft upon which a dowser is mounted, a latch and a cam mounted on saidshaft and rotatable therewith, a swingable control plate adapted to have the lower end thereof swung outward by the keeper when the magnet is deenergized, means on said control plate for engaging said latch when the lower end of said control plate is swung outward, said plate being arranged to swing and disengage said means and latch when the magnet is energized and the keeper drawn thereto, means on said plate'engaging said cam for holding said dowser in a raised position when saidmagnet is energized, a

-motor switch, andmeans on saidshaft for opening said switch when the magnet is deenergized and the dowser fallsinto light obstructing position;

1Q. A dowser control mechanism for motionpicture projecting machines comprising an electro-magnet, a keeper, a shaft upon which a dowser is mounted, a latch and a cam mounted on said shaft androtatable therewith, a swingable control plate, an outstanding lug on said control plate positioned by the keeper for engaging said latch to prevent the turning of said shaft and the raising of said dowser when the-magnet is deenergized, said plate being arranged to swing and disengage said lug andlatch when the magnet is energized and the keeper drawn thereto, means on said plate engaging said cam for holding said dowser in a raised position when said magnet is energized, a motor switch, and means on said shaft for opening said switch when the magnet is deenergized and the dowser falls into light obstructing position.

11. A dowser control mechanism for mo tion picture prdjecting machines comprising an electro-magnet, a keeper, a shaft upon which a dowser is mounted, a latch and a cam mounted on saidshaft and rotatable therewith, a swingable control plate adapted to have the lower end thereof swung outward by the keeper when the magnet is deenergized, an outstanding lug on said control plate for engaging said latch when the lower end of said control plate is swung outward, said plate being arranged to swing and disengage said lug and latch when the magnet is energized and the keePer'draWn thereto, means on said plate engaging said cam for holding. said dowser in a raised position when said magnet is energized, a motor switch, and means on said shaft for opening said switch when the magnet is deenergized and the dowser falls into light obstructing position.

12. A dowser control mechanism for motion picture projecting machines comprising an electro-magnet, a keeper, a shaft upon ,when the magnet is deenergized, said plate b81119: arrangedto'swmg and disengage said means and lat-ch when the magnet is energized and the keeper drawn thereto, a-notch in the lower end of said plate for receiving said cam to hold said dowser in a raised position when said magnet is energized, a motor switch, and

means on said shaft for opening said switch when the magnet. is deenergized and the dowser falls into light obstructing positionl l 13. A dowser control mechanism for mo-1v tion picture projecting machines comprising an electromagnet, a keeper, a shaft upon which a dowser is mounted, a latch and a cam mounted on said shaft and rotatable therewith, a swingable control plate adapted to have the lower end thereof swung outward by the keeper when the magnet is deenergized, means on said control plate for engaging said latch when the lower end of said control plate is swung outward, said plate being arranged to swing and disengage said means and lateh when the magnet is energized and the keeper drawn thereto, a'notch in the lowerend of said plate for receiving said cam to hold said dowser in a raised position when said magnet is energized, a motor switch, and means on said shaft for opening said switch when the magnetis deenergized and the dowser falls into light obstructing position. L

14; A dowser control mechanism for motion picture projecting machines comprising an electro-magnet, a keeperja shaft upon which a dowser is mounted, a latch and a cam mounted on said shaft and rotatable therewith, a swingably mounted control plate,

v means for pulling said keeper away from said magnet when the magnet is deenergized, an outstanding lug on the control plate. said keeper being adapted when the magnet is deenergized to press against and swing the lower end of said control'plate outward to en gage sa d outstanding lug with said latch to prevent the turningof said shaft and the raising of the dowser, and means for swingmg the lower end of said control plate inward to disengage said latch and said outstanding lug when the magnet is energized and the keeper drawn away from said plate to permit the dowser to be raised. 15. A dowser control mechanism for motion picture projecting machines comprising an electro-magnet, 'a keeper. a shaft upon which a dowser is mounted. a latch and a cam mounted on said shaft and rotatable therewith, a swingably mounted control plate. means for pulling said keeper away fromsaid magnet when the magnet is denergized, an

outstanding lug on the control plate, said keeper being adapted when the magnet is deenergized to press against and swing the lower end of said control plate outward to engage said outstanding lug with said latch to prevent the turning of said shaft and the raising of the dowser, means for swinging the lower end of said control plate inward to disengage said latch and said outstanding'lng when the magnet is energized and the keeper drawn away from said plate to permit the dowscr to he raised, and means on said plate engaging said cam for holding said dowser in a raised gized,

16. A dowser control mechanism for motion picture projecting machines comprising an electro-magnet, a keeper, a shaft upon which a dowser is mounted, a latch and a cam mounted on said shaft and rotatable therewith, a swingably mounted control plate, means for pulling said keeper away from said magnet when the magnet is deenergized, an outstanding lug on the control plate, said keeper being adapted when the magnet is deenergized to press against and swing the lower end of said control plate outward to engage said outstandinglug with said latch, to prevent the turning of said shaft and the raising of the dowser, means for swinging the lower end of said control plate inward to dis engage said latch and said outstanding lug when themagnet is energized and the keeper drawn away from said plate to permit the dowser to be raised, and means on said plate engaging said cam for holding said dowser in a raised position when said magnet is energized, said last named means adapted to release said cam to permit the dowser to drop by gravity when the magnet is deenergized. A dowser control mechanism for met o'n picture; projecting machines comprising an electro-magnet, a. keeper, a shaft upon which a dowser is mounted, a latch and a cam mounted on said shaft and rotatable therewith, a swingahly mounted control plate, means-for pulling said keeper away from said, magnet when the magnet is deenergizechan outstanding lug on the control plate, said keeper being adapted when the magnet is deenergized to press'against and swing the lower end of said control plate outward to engage said outstanding lug with said latch to prevent the turning of said shaft and the raising of the. dowser, means for swinging the lower end of said control plate inward to position when said magnet is enerdisengage said latch andsaid outstanding lug when the magnet is energized and the keeper drawn away from said plate to permit the dowser to he raised, a motor switch, and means on said shaft for opening said switch when the magnet is deenergized and the dowser falls.

18. A dowser control mechanism for motion picture projecting machines comprising an electro-n'iagnet, a keeper, a shaft upon which a dowser is mounted, a latch and a cam mounted on said shaft and rotatable there with, a swingably mounted control plate, means for pulling said keeper away from said magnet when the magnet is dcenergized, and outstanding lug on the control plate, said keeper being adapted when the magnet is deenergized to press against and swing the lower end of said control plate outward to engage said outstandii'i lug with said latch to prevent the turning of said shaft and the rais ingoi the dowser, means for swinging the lower end of said control plate inward to disengage said latch and said outstanding lug when the magnet energized and the keeper drawn away from said plate to permit the dowser to he raised, means on said plate ongagingsaid cam for holding said dowser'in a raised position when said magnet is energized, a motor switch, and means on said shaft for opening said switch when the magnet is decncrgized and the dowser falls.

19. A dowser control mechanism for motion picture projecting machines con'iprising an elcctro-niagnet, a keeper, a shaft upon which a dowser is mounted, a latch and a cam mounted on said shaft and rotatable there with, a swingably mountedv control plate, means for pulling said keeper away from said magnet when the magnet is deenergized, an outstanding lug on the control plate, said keeper being adapted when the magnet is deenergized to press against and swing the lower end of said control plate outward to engage said outstanding lug with said latch to prevent the turning of said shaft and the raising of the dowser, means for swinging the lower end of said control plate inward to disengage said latch and said outstanding lug when the magnet is energized and the keeper drawn away from said plate to permit the dowser to he raised, means on said plate en-.

gaging said cam for holding said dowser in a raised )osition when said ma net is ener ized X") b 7 said last named means adapted to be released from said cam by the keeper striking against said plate to permit the dowser to drop by gravity when the magnet is deenergizcd, a motor switch, and means on said shaft for opening said switch when the magnet is deenergized and the dowser falls.

20. Dowser control mechanism such as described in claim 1 having manual means for swinging the control plate inward to permit the raising of said dowser when the magnet is deenergized,

21. Dowser control mechanism such as described in claim 1 havingn'ianual means on the outside of said casing for operating a release to swing said control plate inward to permit the raising of the dowser out of light I obstructing position when the magnet is deenergized.

22. Dowser control mechanism such as deill scribed in claim having manual means thereon for swinging said control plate outward to disengage the means on said control plate from said'cam to permit said dowser to fall into light obstructing position when the magnet is energized.

23. Dowser control mechanism such as described in claim 1 comprising manual means on the outside of the casing having a rod adapted to engage the control plate to swing the same outward to disengage the means onsaid plate from said cam to permit the .dowser to fall into light obstructing position when the magnet is energized.

24- Dowser co trolnmechan n m u hasde;

scribed in claim 1 having manual means for swinging the control plate inward to permit the raising of said dowser when the magnet is deenergized, and manual means on said casingfor swinging said control plate outward to disengage the means on said control plate from said cam to permit said dowser to fall into light obstructing position when the magnet is energized. 1

said magnet,- a shaft upon which a dowser is mounted, a latch and a cam mounted on said shaft and rotated therewith, a swingable con- ;trol plate normally urged toward said keeper means for urging the keeper toward saidplate, means on said control plate positioned by the keeper for engaging said latch to prevent the turning of said shaft and the raising of said dowser when the magnet is deenergiied, said plate being arranged to swing and disengage said means and latch when the magnet' is energized and the keeper drawn. thereto, and means on said plate engaging .Sl-ld cam for holding said dowser in a raised positionwhen said magnet is energized.

In testimony whereof 'we have signed our names to this specification.

' THOMAS TWADDEL ALLEN. JOHN FRANCIS ADAMS. J. STRUTHERS DUNN. 

